Project vinh phuc flood risk and water resource management phu luc

Project: Vinh Phuc Flood risk and Water resource Management APPENDIX HYDROLOGICAL CALCULATION GEOLOGICAL AND HYDROLOGICAL CHARACTERISTICS OF THE STUDY AREA Location of basin Thanh Lanh reservoir was built in Trung My commune, Binh Xuyen district, Vinh Phuc province The Reservoir was started the construction in 2001 and put into use in 2006 Headworks cluster includes main dam, intake culvert placed left abutment of the main dam, auxiliary dams and spillway located in the middle of the Auxiliary Dam No line Thanh Lanh reservoir was built with the tasks to irrigate agricultural land of 1200ha of four Communes of Trung My, Thien Ke, Ba Hien and Son Loi In addition, it has also used to prevent flooding for communes in the lowland area of Binh Xuyen district, supplying the living water for residents in the beneficial area in the dry season… Table 1-1: The morphological features of Thanh Lanh reservoir basin Flv (km2) 22.3 Name of resevoir Thanh Lanh Ls(km) 7.8 Js(‰) 28.1 Table 1-2 Main parameters of Thanh Lanh reservoir No Parameter I Reservoir Whole area of basin Total storage Effective storage Dead storage NWL Hi-rising WL Dead level II Earth Dam Main dam Structure Elevation of dam crest Elevation of parapet wall crest Width of dam crest Length of dam crest Max height of dam Upstream slope coefficient Unit Value Km2 106m3 106m3 106m3 m m m 23.0 10,621 9,892 0.729 +76.60 +77.50 +62.20 m m m m m Homogeneous earth dam +78.10 +79.10 5.0 362.0 29.0 2.75 - 4.5 Report on Dam safety - Thanh Lanh reservoir – Vinh Phuc prvince 46 Project: Vinh Phuc Flood risk and Water resource Management No Parameter Elevation of upstream berm Width of upstream berm Downstream slope coefficient Elevation of downstream berm Width of downstream berm Auxiliary dam Structure Elevation of dam crest Width of dam crest Length of dam crest Max dam height Hmax Upstream slope coefficient Downstream slope coefficient Auxiliary dam Structure Elevation of dam crest Width of dam crest Length of dam crest Max dam height Hmax Upstream slope coefficient Downstream slope coefficient III Intake culvert Type of culvert Elevation of intake-culvert sill Dimension Length of culvert Slope of culvert bottom ic Flow regime IV Spillway Form of spillway Unit m m Width of water spill Number of valve gates Form of valve-gate Elevation of spillway sill Continuous form Form of dissipation m unit Value +68.10 3.5 2.75 – 3.0 +60.10 3.5 m m m m m m m m m m Homogeneous earth dam +79.10 5.0 76.0 12.0 3.0 2.75 Homogeneous earth dam +79.10 5.0 159.0 9.1 3.0 2.75 RC box culvert +60.0 100 112.0 0.01 Unpressurized m m m m Spill of pragmatic ophixerop with valve gate 10.0 Arch-shaped valve-gate +71.6 Chute Dissipation tank Report on Dam safety - Thanh Lanh reservoir – Vinh Phuc prvince 47 Project: Vinh Phuc Flood risk and Water resource Management Figure 1-1 Basin of Thanh Lanh Reservoir I.1 Topographical and geomorphological characteristics The study area is generally characterized as hilly terrain The Northeast of the basin is limited by high mountain range with the elevations lowerinf from the Southeast from + 1000m to 400m The sloping direction is from the Northwest - Southeast towards the Thanh Lanh reservoir I.2 Hydrological Measurement of the project area Near the study basin, Vinh Yen meteorological station managed by the Department of Meteorology and Hydrology has a long-time measurement with assured quality of measurement and is about 8km Southwest of reservoir Thus, the report is proposed to use data of Vinh Yen meteorological station to calculate the study basin Report on Dam safety - Thanh Lanh reservoir – Vinh Phuc prvince 48 Project: Vinh Phuc Flood risk and Water resource Management I.3 Tốc độ gió I.3.1 Average wind speed Average wind speed in the project area is summed up from the data measured in the reality of Vinh Yen meteorological station The results are presented in the following table: Table 1-3: Average wind speed in the project location Station I II III IV V VI VII VIII IX X XI XII Năm Vinh Yen (m/s) 1,6 1,9 2,0 2,3 2,2 1,9 1,9 1,5 1,3 1,3 1,3 1,4 1,7 I.3.2 Maximum indirection wind speed Maximum indirection wind speed in the study area is calculated according to data of Vinh Yen station The results of calculating maximum wind speed corresponding to design frequencies are shown in table 1-6 The details of calculation and frequency lines are mentioned in the table Table 1-4: Maximum indirection wind speed corresponding to design frequencies (m/s) Wind direction Average value Cv Cs Indirection 18.64 0.25 0.05 29.7 Frequency (%) 25 28.3 26.4 21.8 50 18.6 I.4 Precipitation causing flood Because Thanh Lanh reservoir has no precipitation measuring data so the report used precipitation data of Vinh Yen station to calculate the characteristics of precipitation causing flood The calculation results are as follows: Table 1-5: Maximum daily precipitation in Vinh Yen station (mm) X1maxTB Cv Cs X0.01% X0.1% X0.2% X0.5% 128.9 0.51 1.80 655.4 504.5 460.0 401.7 Frequency line and detailed calculation are shown in the table X1% 358.1 X1.5% 332.7 II HYDROLOGICAL CHARACTERISTICS II.1 Design flood flow Because Thanh Lanh has no flow measuring data while the area of reservoir’s basin is 22.3 km2, so according to Standard C6-77, the report of design flood calculation of Thanh Lam reservoir is conducted by using limited intensity experience formula method Report on Dam safety - Thanh Lanh reservoir – Vinh Phuc prvince 49 Project: Vinh Phuc Flood risk and Water resource Management QP = Ap.α.Hnp.F + : The highest discharge corresponding to frequency P + : Coefficient of flood flow– with + HP : Maximum daily precipitation corresponding to design frequency p + F : Basin area (km2), F = 23.0 km2 = 0.75 The calculation results are presented in the below table Table 1-6: Results of design flood peak calculation in Thanh Lanh basin P% 0.01 0.10 0.20 0.50 1.00 Hp%(mm) 655.4 504.5 460 401.7 358.1 Ap 0.062 0.058 0.057 0.055 0.053 Qp (m /s) 705 505 450 379 329 Formula to calculate total design flood discharge: WP =αHPF * 1000 1.50 332.7 0.052 301 The calculation results are presented in table 1-7 as follows: Table 1-7: Results of total design flood peak calculation in Thanh Lanh basin P (%) 0.01 0.10 0.20 0.50 1.00 1.50 Wp (10 m ) 11.306 8.702 7.935 6.929 6.177 5.739 Design flood hydrograph of the study basin is established by triangular shape with the time of water lowering by 1.5 times time of flood rising III TABLES Table of Max daily rainfall value corresponding to design frequency at Vinh Yen station No 10 P (%) 0.01 0.10 0.20 0.33 0.50 1.00 1.50 2.00 3.00 5.00 X (mm) 655.38 504.49 459.97 428.05 401.71 358.06 332.67 314.71 289.46 257.73 Report on Dam safety - Thanh Lanh reservoir – Vinh Phuc prvince Year 10000.000 1000.000 500.000 303.030 200.000 100.000 66.667 50.000 33.333 20.000 50 Project: Vinh Phuc Flood risk and Water resource Management FFC 2008 © Nghiem Tien Lam ĐƯỜNG TẦN SUẤT MƯA NGÀY LỚN NHẤT - VĨNH YÊN 700 X1max Vĩnh Yên TB=128.86, Cv=0.44, Cs=1.44 650 Tần suất lý luận TB=128.86, Cv=0.51, Cs=1.80 600 550 500 Lượng mưa, X (mm) 450 400 350 300 250 200 150 100 50 0.01 0.1 10 20 30 40 50 60 Tần suất, P(%) Report on Dam safety - Thanh Lanh reservoir – Vinh Phuc prvince 70 80 90 99 99.9 99.99 © FFC 2008 51 Project: Vinh Phuc Flood risk and Water resource Management FFC 2008 © Nghiem Tien Lam ĐƯỜNG TẦN SUẤT GIĨ MAX VƠ HƯỚNG - TRẠM VĨNH N 37 35 Gió max vơ hướng trạm Vĩnh n TB=18.64, Cv=0.23, Cs=0.05 33 Tần suất lý luận TB=18.64, Cv=0.25, Cs=0.05 31 29 27 25 Vận tốc gió, V (m/s) 23 21 19 17 15 13 11 0.01 0.1 10 20 30 40 50 60 Tần suất, P(%) Report on Dam safety - Thanh Lanh reservoir – Vinh Phuc prvince 70 80 90 99 99.9 99.99 © FFC 2008 52 Project: Vinh Phuc Flood risk and Water resource Management Design flood of Xa Huong reservoir corresponding to various frequencies Time (hr) 0.00 0.50 1.00 1.50 2.00 2.50 3.00 3.50 3.57 4.00 4.50 5.00 5.50 6.00 6.50 7.00 7.50 8.00 8.50 8.91 Q0.01% 0.0 98.8 197.7 296.5 395.3 494.1 593.0 691.8 704.7 647.4 581.5 515.6 449.7 383.9 318.0 252.1 186.2 120.3 54.4 0.0 Time (hr) 0.00 0.50 1.00 1.50 2.00 2.50 3.00 3.50 3.83 4.00 4.50 5.00 5.50 6.00 6.50 7.00 7.50 8.00 8.50 9.00 9.50 9.57 Q0.1% 0.0 66.0 132.0 197.9 263.9 329.9 395.9 461.8 505.2 490.1 446.1 402.1 358.1 314.1 270.1 226.2 182.2 138.2 94.2 50.2 6.2 0.0 Time (hr) 0.00 0.50 1.00 1.50 2.00 2.50 3.00 3.50 3.92 4.00 4.50 5.00 5.50 6.00 6.50 7.00 7.50 8.00 8.50 9.00 9.50 9.80 Report on Dam safety - Thanh Lanh reservoir – Vinh Phuc prvince Q0.2% 0.0 57.4 114.8 172.2 229.6 287.0 344.4 401.8 449.9 443.7 405.5 367.2 328.9 290.7 252.4 214.2 175.9 137.6 99.4 61.1 22.8 Time (hr) 0.00 0.50 1.00 1.50 2.00 2.50 3.00 3.50 4.00 4.06 4.50 5.00 5.50 6.00 6.50 7.00 7.50 8.00 8.50 9.00 9.50 10.00 10.15 Q0.5% 0.0 46.7 93.5 140.2 186.9 233.7 280.4 327.2 373.9 379.4 351.9 320.7 289.6 258.4 227.3 196.1 164.9 133.8 102.6 71.5 40.3 9.2 0.0 Time (hr) 0.00 0.50 1.00 1.50 2.00 2.50 3.00 3.50 4.00 4.17 4.50 5.00 5.50 6.00 6.50 7.00 7.50 8.00 8.50 9.00 9.50 10.00 10.42 Q1.0% 0.0 39.5 79.1 118.6 158.1 197.6 237.2 276.7 316.2 329.4 311.9 285.5 259.2 232.8 206.5 180.1 153.8 127.4 101.1 74.7 48.4 22.0 0.0 Time (hr) 0.00 0.50 1.00 1.50 2.00 2.50 3.00 3.50 4.00 4.24 4.50 5.00 5.50 6.00 6.50 7.00 7.50 8.00 8.50 9.00 9.50 10.00 10.50 10.59 Q1.5% 0.0 35.5 71.1 106.6 142.1 177.7 213.2 248.8 284.3 301.1 288.6 264.9 241.2 217.5 193.8 170.1 146.4 122.7 99.0 75.3 51.7 28.0 4.3 0.0 53 Project: Vinh Phuc Flood risk and Water resource Management APPENDIX CALCULATION OF FOLLD REGULATION IV CALCULATION OBJECTIVE The flood regulation calculation is aimed to examine the possibility of discharge of the flood discharge work, the flood water level is the basis for determining the dam crest elevation V CALCULATION FREQUENCY Thanh Lanh Reservoir was built in the years of 2001 to 2006 following the design regulations of that period, of grade III, the frequency of desing and check flood pevention of the reservoir is Pdesign = 1.5% and Pcheck = 0.5% Under the current regulation QCVN 04-05: 2012 / BNNPTNT: irrigation works The main provisions of the design and Thanh Lanh reservoirs belongs to Work of grade II, so that Pdesign = 1% and Pcheck = 0.2% In addition, at the request of the World Bank, the reservoir has a large number of households of 25 households living downstream, hence it is required to calculate the frequency of check flood with P = 0.01% Table 2-2 Calculation sequency of flood regulation Name of reservoir Thanh Lanh Work grade PTK (%) PKT1 (%) PKT2 (%) II 0,2 0,01 VI CALCULATION CASES Conducting calculating the flood regulation for different combinations to determine flood levels and discharge flow corresponding to current spillway B spillway = 10m, Bincidental spiwwal = 30m VII CALCULATION METHOD Flood regulation calculation is conducted by using DTL2002 program of Water Resources University Algorithm of the code is based n equilibrium equation as follows: dV =Q−q dt Report on Dam safety - Thanh Lanh reservoir – Vinh Phuc prvince (2.1) 54 Project: Vinh Phuc Flood risk and Water resource Management With the following marginal conditions: - Volumetric characteristic of reservoir V = f1 (Z) (2.2) - Downstream water level characteristic Zh = f2 (q) (2.3) Where: V: volume; t: time; Q: flood inflow; q: discharge through spillway; Z: water level of reservoir; Zh: downstream water level In the case of multi-spillway working together: Q = Σqi (2.4) Where Qxi is discharge through water outlet number, it can be separated: - Superfacial spillway with entirely opened water gate qi = σn ε.m B 2g H03/2 (2.5) - Superfacial spillway with partly opened water gate qi = ε α A B 2g(H − hz ) (2.6) - Bottom water outlet: qi = µ ω 2g(H − hz ) (2.7) - Discharge overtopping the self-flipping spillway when not flipping: Applying the flow calculation formulas showed in section 2.3.2 Hydraulic Calculation of Spillway corresponding to designed structures - Discharge overtopping the accidental spillway: Applying calculation formula for flow overtopping the broad-crest spillway, hydraulic calculations of spillway corresponding to designed structures Report on Dam safety - Thanh Lanh reservoir – Vinh Phuc prvince 55 Project: Vinh Phuc Flood risk and Water resource Management Table 4-4 Mechanical and physical indicators of fill soil and dam foundation Soil layer γ (KN/m3) C(KG/cm2) ϕ(degree) K(cm/s) 18.2 19.2 17.7 18.5 18.3 21.0 17.0 22.0 25.0 29.0 18012’ 14051’ 16036’ 15049’ 16010’ 1.0× 10-5 1.625× 10-7 4.17× 10-6 9.0× 10-6 6.6× 10-6 Dam-fill layer Layer 1a Layer Layer 3a Layer I.2 Calculation cross-section Calculation was made for main-dam slope, with largest dam height and mst dangerous to the work 105 Elevation 95 85 75 65 55 45 35 25 15 -20 20 40 60 80 100 120 140 160 180 200 220 240 260 280 300 160 180 200 220 240 260 280 300 Distance 105 Elevation 95 85 75 65 55 45 35 25 15 -20 20 40 60 80 100 120 140 Distance Figure 4-6 Diagram of calculation x-section of Thanh Lanh reservoir Report on Dam safety - Thanh Lanh reservoir – Vinh Phuc prvince 75 Project: Vinh Phuc Flood risk and Water resource Management I.3 Case of calculation Calculation cases - CASE 1: Upstream is NWL +76.6 m, no water at downstream - CASE 2: Upstream is DFWL +77.12 m, water level equivalent at downstream - CASE 3: Upstream is CFWL +78.74 m, water level equivalent at downstream II CALCULATION RESULTS Case of NWL 105 85 75 Elevation 95 65 e -0 m ³/s e c 55 45 35 25 15 -20 20 40 60 80 100 120 140 160 180 200 220 240 260 280 300 260 280 300 Distance Figure 4-2 Calculation result of dam seepage check TH1 Case of DFWL 105 85 75 65 45 35 25 e -0 m ³/s e c 55 Elevation 95 15 -20 20 40 60 80 100 120 140 160 180 200 220 240 Distance Figure 4-3 Calculation result of dam seepage check TH2 Report on Dam safety - Thanh Lanh reservoir – Vinh Phuc prvince 76 Project: Vinh Phuc Flood risk and Water resource Management Case of CFWL 105 85 75 65 Elevation 95 e -0 m ³/s e c 55 45 35 25 15 -20 20 40 60 80 100 120 140 160 180 200 220 240 260 280 300 Distance Figure 4-4 Calculation result of dam seepage check TH3 Table 4-5 Calculation results of seepage at the main dam No Calculation case Dam TH1 TH2 TH3 Main dam Main dam Main dam Seepage flow q(10-6m3/s/m) 3.432 3.851 4.232 Jxymax 3.25 4.12 4.90 Gradient value calculated is high, appearing at the locations such as the cutoff position of dam, stone pile for drainage, at these locations the transitional treatment was applied so that there is no underground erosion or land drift Conclusion: In both cases of calculation, the biggest seepage Gradient value appears at the transitional treated locations, so that the dam assures the safety in terms of seepage Report on Dam safety - Thanh Lanh reservoir – Vinh Phuc prvince 77 Project: Vinh Phuc Flood risk and Water resource Management APPENDIX CALCULATION OF DAM STABILITY CHECK I CALCULATION METHOD AND PROGRAMME This applied calculation program is SLOPE/W This is a software applied by using the critical equilibrium theory to identify the stability coefficient of rock or soil slopes, that was programmed by GEO - SLOPE International Ltd – Canada This program enables to calculate simultaneously with different methods Calculate the stability of dam slope using Bishop, Jambu methods which are currently popular, produce satisfactory accurate results, and are simple to calculate For the purpose of ensuring the safety in the calculation, the following only present the outcomes of the used method producing the lowest coefficient of safety I CALCULATION DOCUMENTS I.1 Calculation cross-section Sections of seepage calculation are used to check the stability of dam slope I.2 Calculation cases Thanh Lanh reservoir is located in Trung My, Binh Xuyen District, Vinh Phuc province which is the work of Grade II Referring to the Appendix of seismic zoning by administrative place and earthquake-resistance work design standard TCXDVN 375-2006, Binh Xuyen District belongs to the earthquake zone of Level VII under scale of MSK64 Under the provisions of the World Bank, the earthquake of Grade VII and the work of Grade II, it is required to calculate with the cases of earthquake According to TCVN 8216-2009, standards of designing the compacted earth dam and requirements of the World Bank, it is required to conduct stability calculations with cases NWL, DFWL, CFWL and NWL with earthquake event: Table 5-6 Combinations of calculating earth dam stability No Case CASE CASE NWL at Upstream +76.6m; no water at downstream DFWL at Upstream +77.12m; water level is equivalent at downstream Combination Slope stability Basic Downstream Basic Downstream Report on Dam safety - Thanh Lanh reservoir – Vinh Phuc prvince 78 Project: Vinh Phuc Flood risk and Water resource Management No Case Combination Slope stability Special Downstream Special Downstream CASE DFWL at Upstream +78.74m; water level is equivalent at downstream NWL at Upstream +76.6m; no water at TH4 downstream, with earthquake grade VII II CALCULATION RESULT OF STABILITY Case of NWL 1.329 105 Elevation 95 85 75 65 55 45 35 25 15 -20 20 40 60 80 100 120 140 160 180 200 220 240 260 280 300 Distance Figure 5-7 Calculation results of dam stability check TH1 Case of DFWL 1.301 105 Elevation 95 85 75 65 55 45 35 25 15 -20 20 40 60 80 100 120 140 160 180 200 220 240 260 280 300 Distance Figure 5-2 Calculation results of dam stability check CASE2 Report on Dam safety - Thanh Lanh reservoir – Vinh Phuc prvince 79 Project: Vinh Phuc Flood risk and Water resource Management Case of CFWL 1.290 105 Elevation 95 85 75 65 55 45 35 25 15 -20 20 40 60 80 100 120 140 160 180 200 220 240 260 280 300 Distance Figure 5-3 Calculation results of dam stability check CASE3 Case of NWL, with earthquake grade 1.208 105 Elevation 95 85 75 65 55 45 35 25 15 -20 20 40 60 80 100 120 140 160 180 200 220 240 260 280 300 Distance Figure 5-4 Calculation results of dam stability check TH4 Table 5-7 Calculation results of dam stability check T T Dam Main dam Main dam Main dam Main dam Kminmin Calculation case Combinatio n Downstream slope CASE CASE CASE TH4 Basic Basic Special Special 1.329 1.301 1.290 1.208 Upstream slope [K] 1.30 1.30 1.10 1.10 Conclusion: In the case of checking for the dam cross-section as above mentioned, conditions for stability and safety of slope sliding are assured Report on Dam safety - Thanh Lanh reservoir – Vinh Phuc prvince 80 Project: Vinh Phuc Flood risk and Water resource Management APPENDIX OUTLINE FOR IMPLEMENTING THE EPP FOR THANH LANH RESERVOIR I OVERVIEW OF EPP The existence of large dams along with reservoirs at the upstream area of residential areas requires the establishment of technical emergency preparation plan for each dam The aim of such plans is to assist relevant agencies in charge of public security in taking proper and necessary measures to prevent casualities and limit physical damages due to the anticipated accidents in case of possible dam failures Each risk-prone dam, reservoir and area all have distinctive characteristics and thus, each EPP shall be prepared, taking specific conditions of the work into account However, some general issues need to be mentioned for each work with the essential EPP So far, the Consultant has still not been able to define the guidance of Vietnam on the requirements for preparing the EPP or instructions such as who shall be assigned with responsibilities related to the preparation and implementation of the EPP Finally, a sample cost estimate for preparing the EPP is also established For benefits-related issue, it is more difficult to determine In general, it is necessarily known that the management of dam safety is better and the EPPs are implemented for the existing dams, resulting in the decrease of the number of average accidents caused by floods II GENERAL REQUIREMENTS FOR EPP With the aim to transform an EPP into an useful tool to prevent disasters and minimize them, it is necessary to have reliable legal instruments enabling relevant agencies in charge of preparating and implementing the EPPs to enforce their necessary powers Such powers will be decentralized and specified in detail for legislative emergency conditions If current laws are seemed to be inadequate for this aim, there is a must for considering the adjustment of legal framework In terms of principle, the organization taking charge of management, operation and maintenance of a specific dam are also mainly responsible for the preparation of the EPP Such organizations should have reasonable related knowledge of risks Report on Dam safety - Thanh Lanh reservoir – Vinh Phuc prvince 81 Project: Vinh Phuc Flood risk and Water resource Management associated with dam and reservoir of a particular work For the Vietnam water resources assistance project, the organizations being primarily responsible for preparation and implementation of the EPP will be hydraulic works exploitation and management companies for each specific work The People’s Committees of the provinces having dams will be able to act as supervisors Other relevant agencies may also be authorized to set up the regulations and rules, prepare, implement, inspect and promote the EPPs The preparation of a detailed EPP for dam and reservoir needs proper maps and figures of river, dam, topography, hydrology, rural and urban infrastructure, population and risks-prone physical assets, etc as well as special skills and computer programs in order to assess the potential impact of numerous different risk scenarios Such tools are unavailable in the Hydraulic Works Exploitation and Management Companies and before the Companies’ possible preparation of the EPPs, it is necessary to make a certain investment and widespread preparation There are many ways to deal with this issue and they can support the Companies through the expected National Dam Safety Agency or relevant technical consultant or institutes Because there is currently no (the expanded) EPP for most of dams and reservoirs, the budget-financed costs and expenses related to the preparation and implementation of the EPPs haven’t been allocated If additional source of the budget can’t be taken from the public, it is forecasted that relevant agencies shall take advantage of existing resources such as manpower, equipment, means of communication as much as possible This will require a very detailed plan and close coordination in communication actions The EPP should be updated annually and submitted to the Provincial People’s Committee for approval III THE EPP FOR THANH LANH RESERVOIR The downstream area of Thanh Lanh dam is Thanh Trung commune, Binh Xuyen, Vinh Phuc Province with the elevation of from +50 to +95m Further distance is Vinh Yen City with dense population of residents and infrastructure facilities there Thanh Lanh reservoir has a storage capacity of over 10 milion m3 of water, any breakage failures to the dam and spillway here may bring about a huge loss for residents and properties in downstream area of the reservoir Report on Dam safety - Thanh Lanh reservoir – Vinh Phuc prvince 82 Project: Vinh Phuc Flood risk and Water resource Management IV OVERVIEW Tam Dao Hydraulic One Member Limited Company is expected to be supported by the National Dam Safety Committee (in case of being establishment on the sepcified term) or the Consultant, and shall be responsible for preparation of the EPP for related dam and reservoir The EPP must be prepared on the basis of close cooperation with relevant agencies in the province in charge of storm and flood prevention, and submitted to the Provincial People’s Committee for approval The plan must be updated and submitted for approval once a year prior to flood season An outline of the EPP, in the form of the list of items in need of inspection and a series of headings related to the EPP and actions, is required The list of such items may be used for the future preparation of the EPP Generally, the subsequent main activities are especially remarkable upon preparation of the (emergency) plans for dam-related potential failures V STRENGTHENING THE SUPERVISION OF HYDRAULIC WORKS EXPLOITATION AND MANAGEMENT COMPANY The EPP needs to start with detailed instructions on dam and auxiliary works monitoring undertaken by the employee of the Hydraulic Works Exploitation and Management Company, particularly the supervision in the stages of extreme rains in the basin or in cases of rising water level of the reservoir The instructions should specify the points in need of special observation, especially in case water level of the reservoir begins to quickly rise The monitoring includes regularly observing seepage water along the dam foot and in any locations along the dam surface where seepage water is known to exist only when water level of the reservoir is high Depending on the number of parameters, for example: - Thick and widespread precipitation in the basin in the prolonged stage; - Precipitation in the water collecting basin in a short-term stage; - Water level of the reservoir and increase of water level in the reservoir; - Increased seepage water amount; or - Seepage water becomes cloudy in the downstream slope or dam foot; - Movement of dam crest or downstream dam surface Report on Dam safety - Thanh Lanh reservoir – Vinh Phuc prvince 83 Project: Vinh Phuc Flood risk and Water resource Management The Hydraulic Works Exploitation and Management Company (HWEM Company) shall calculate reasonable alarming level in a more detailed manner, make adjustments subject to the actual situation VI DEFINITIONS AND NOTIFICATION OF ALARM LEVELS For each alarm level or a specific situation, the measures that will later be widely implemented should be initiated when the conditions become deteriorated and the situation becomes more serious These measures will start with internal information from the Hydraulic Works Exploitation and Management (HWEM) Company, and increase its intensity along with the severity of the situation, for example: - The up-to-date information shall be provided continuously for the Management of the hydraulic works exploitation and management company; - Suspend the vacation of a certain number of officers of the HWEM Company; - Local police and rescue forces must be in an alarming condition; - Some certain experts and operators equipped with devices are dispatched to the dam or other locations; - Notification via local stations and radio stations; - Officials of Provincial People’s Committee (PPC), military, public works department and other departments have been put on high alert and instructed; - Mobilize support units (fire fighting forces, military, Red Cross) and equipment; - Public information and ensure that everyone is informed; - Block a certain number of routes, stop or strengthen buses and trains; - Mobilize helicopters, boats and transport equipment; - Prepare refuges; - Require relocation for the most dangerous areas; - Require the complete relocation; - Notify the emergency The alarm levels should be clearly defined, and the definitions should be distributed to all related staff and agencies immediately after the EPP is approved Local people need to be fully aware of the levels to be informed clearly by sirens or something Report on Dam safety - Thanh Lanh reservoir – Vinh Phuc prvince 84 Project: Vinh Phuc Flood risk and Water resource Management similar After consultation with local authorities, Hydraulic Works Exploitation Company will provide guidance so that the public alarm achieves the best results VII DATA COLLECTION To establish an EPP, HWEM Company must first require detailed maps of the possibly affected entire region Houses, roads, bridges, culverts, highlands, lowlands, dam banks, canals, etc must be represented on the maps Especially for the preparation of dam break analysis, it is necessary to have detailed information, including the section of the river basin, main obstacles to the progress of flood waves in the channel of the river or alluvial grounds, hollows may temporarily act as reservoirs, levees, water divisions, dikes, ditches, creeks and other topographical factors affecting flood waves The terrain map must extend beyond the project area in order to determine access routes, areas and works (such as schools and community halls) which can serve as a refuges and destinations for flood victims’ relocation There is a must for identifying hospitals near flood-prone areas and notifying their possible tasks in the event of casualties from dam break VIII DAM-BREAK ANALYSIS It is necessary to carry out a dam break analysis to map the boundaries of the areas which may be affected by floods It is recommended to implement the analysis for many different conditions, e.g., for normal water level, reservoir’s water level with maximum flood load, a quickly opened hole in the dam body, for a lot of preliminary cases, for example, for a flooded alluvial ground, relatively dry conditions, high surface water currents and downstream river branches Moreover, computer programs for analyzing dam break can be run for coefficients of roughness and some possible measures to minimize or otherwise, affect flood conditions in some locations such as deceleration of flood speed near residential areas, or improving of roads to access or exit from several certain areas The impact of obstacles in the channel of river or flood grounds should also be evaluated on regulatory standpoint to limit flood level on the river, not only in the catastrophic cases but also for "normally" extreme floods Most of the possible measures for minimizing the impact of extreme flood discharge shall not be Report on Dam safety - Thanh Lanh reservoir – Vinh Phuc prvince 85 Project: Vinh Phuc Flood risk and Water resource Management implemented in the short term but used as planning tools, and policy for future river basin should be carried out gradually IX FLOODING MAP Dam break analysis shall help identify clearly the most dangerous areas in case of the occurrences of disasters Results of the analysis will be presented in the flooding maps, with descriptions of possible depth, flood velocity (as a sign of potential dangerous conditions), progression of discontinuous waves in the basin, time for rescue operations Whenever a preliminary dam break analysis may schematically indicate the above flood parameters, dam break analysis soon will be upgraded under the related better similar conditions Especially the influence of the (slightly) improved embankment is used for road, railway, irrigation, flood prevention, mud and soil piles along canals are also worthy of concern At these positions, the maximum velocity of the flood can also increase, making it impossible to access the embankments or roads and causing landslides, destroying partly or wholly these embankments A network of high obstacles in alluvial areas may divert flood flow and cause more serious conditions at the positions where these conditions are not desired The flooding maps for selected conditions must be available to give to the key agencies related to the physical planning of the area and relevant authorities related to the possibly rescue operations (province, city, police, fire, hospitals, military, etc.) Such maps need to be updated and redistributed in case the conditions of the important changes are determined Number of agencies necessarily getting the maps (and other information) depends on the severity of the conditions, and generally the function of reservoir’s water accumulation, dam height and directly affected area X ORGANIZATIONAL ISSUES Although HWEM Company could be responsible for preparing and maintaining an EPP, most of the activities after a catastrophic event are carried out by other agencies The mission of HWEM Company for the dam and reservoir is to prevent critical situations Assuming that the emergencies occur, HWEM Company shall take all initial measures possible to avoid a disaster When the conditions become more severe, the Company should not wait for the superiors’ warning and responsibility Report on Dam safety - Thanh Lanh reservoir – Vinh Phuc prvince 86 Project: Vinh Phuc Flood risk and Water resource Management assignment In case of the occurrence of these conditions, it is necessary to clearly define who is responsible A detailed plan with the extended information system must be sustained continuously until the occurrence of a disaster The Company must first prepare an EPP for internal purposes in flood conditions and when the manifestations of the dam require more attention The HWEM Company's internal organization shall respond at the first alarm level and inform higher authorities of the concerns and possible consequences In the next higher alarm level, probably the support of other organizations is needed and a part of responsibility can be transferred to such organizations For these cases, there should be a detailed planning and ready information for necessary moves It should be aware that in bad weather conditions, there will be no electricity, the roads may be flooded, telephone lines may be damaged and the publication of prints, map photocopies and planning documents or other directives cannot be done When the situation became serious, the relevant authorities of the province will carry out all their responsibilities and will need to be provided with the plans for actions to be taken which were established in the previous stage These plans should include organizational issues for expected emergency operations, and state clearly the responsibilities and communication for all decentralized (but well-coordinated) activities and actions, depending on specific situation The relevant authority is, under the EPP, responsible for a number of particular activities and inputs in any alert phase, and should be fully informed of any changes to the EPP Also similar to the organizations designated to support activities, for example, means of transportation, equipment, material resources and other inputs are required to be ready in case of disasters XI PROCESS In the lowest alarm level, the relatively simple internal application process of HWEM Company will remain in effect as the process for monitoring and management of dam and auxiliary works When the situation became worse, and the next alarm level starts, the normal operation process of HWEM Company will be supplemented and replaced by a new process focusing on the implementation of the EPP The main management guidelines for the dam will be valid and the dam management will be implemented by the experts of HWEM Company as specified in Report on Dam safety - Thanh Lanh reservoir – Vinh Phuc prvince 87 Project: Vinh Phuc Flood risk and Water resource Management the Company's process for that year Other agencies have no authority to make temporary decisions as to whether spillway gate or other water intake gates or discharge gates open or not Processes for higher alarm levels will transfer the entire responsibilities for the implementation of EPP to the higher authorities (preferably PPC) These processes have a clear allocation of responsibilities and authorization for certain agencies with cooperation and support in emergency operations The EPP should include the plans of clear organization, then it can easily follow the levels of emergency operations These plans should also include main communication routes and procedures to follow for a certain number of activities, such as requesting the help from the Central government and more support from the military forces In case the situation becomes deteriorated, and the relocation becomes the only option, the relocated area shall be protected by police forces or other armed forces The EPP also proposes some provisions for these conditions and they will be discussed with law enforcement agencies responsible for maintaining order and laws The last provisions should include arrangements for bringing necessary forces (such as the Red Cross and similar forces) to higher residential area in the heart of the flooded areas XII COMMUNICATIONS Communication is a vital part of any emergency plan In the very special conditions, most of the means of communication can be broken The EPP should take into account this fact and identify the means of communication that can be used in emergency conditions Ordinary telephone lines and mobile phones cannot be used in extreme conditions Radio communication can solve part of the problem In this regard, the police and armed forces involved in preparing the EPP are vital First of all, the communication between damp field and headquarters of the HWEM Company shall be secured The lines of communication must be active at all times, and the information about water level can be read at the headquarters of the HWEM Company at any given time During regular dam inspection, dam safety Report on Dam safety - Thanh Lanh reservoir – Vinh Phuc prvince 88 Project: Vinh Phuc Flood risk and Water resource Management inspector must pay attention to the means of communication and communication processes established for each dam (or auxiliary dam) Secondly, the communication with higher levels should be well-structured When the situation of the dam becomes worse, and when the responsibilities are beyond the capacity of the HWEM Company, a higher authority must be able to manage smoothly (maybe a part of) the responsibilities and continue to cooperate in the implementation of the EPP In such a situation, the means of communication needs to be able to receive multiple incoming calls The contacts and communication processes must be clearly and fully documented All agencies with primary responsibilities for preparing the emergency plan shall get a copy of these procedures as well as the directives and supporting guidance XIII TRAINING AND MOCK-UP FOR EPP An EPP shall include the training and rehearsal programs for a selected number of components in the EPP It is the best to have a need analysis as the basis for the program The rehearsal programs must be prepared in conjunction with other relevant agencies Training and rehearsal shall focus on the components that the parties involved are not familiar XIV PARTICIPATION BY AND INFORMATION OF THE COMMUNITY The main beneficiaries of the EPP is the residents generally who may be affected by the risks of possible dam failure In order to achieve their full cooperation, raising public awareness and support received from the public are essential The EPP must address the issue of public awareness as an important issue, because of the lack of public awareness, support and involvement, any EPPs become useless Once the draft of the EPP was established and approved by the PPC, the public must be informed of the characteristics of the dam, possibly risks, measures to be implemented and plans to be prepared to avoid adverse impacts or mitigate the consequences For this purpose, types of information shall be conveyed to the public Report on Dam safety - Thanh Lanh reservoir – Vinh Phuc prvince 89 ... reservoir – Vinh Phuc prvince 81 Project: Vinh Phuc Flood risk and Water resource Management associated with dam and reservoir of a particular work For the Vietnam water resources assistance project, ... reservoir – Vinh Phuc prvince 0.00 66 Project: Vinh Phuc Flood risk and Water resource Management Report on Dam safety - Thanh Lanh reservoir – Vinh Phuc prvince... safety - Thanh Lanh reservoir – Vinh Phuc prvince 74 Project: Vinh Phuc Flood risk and Water resource Management Table 4-4 Mechanical and physical indicators of fill soil and dam foundation Soil layer